Guns and Ammo magazine did an article on building a switch caliber 1911 some years bback might want to see if you can find a copy. It is doable, as none of the parts required are registered or controlled beyond commercial laws. - dan
Well that is the debate, on your registration it states that any cartridge change has to be called in, so trying to work out if anyone has done this and if the gun then gets changed to be "multi cartridge". I noticed on the registration the only thing that is listed is barrel length, so keeping a 5in barrel would not change any part of the physical registration but based on the wording you have 30 days to notify the CFO if you changed the cartridge it is chambered in.
It may be that issue of a new registration certificate is no longer possible. The handgun freeze on transfers is accomplished by non-issue of registration certificates.